Bats May Have Triggered Ebola Outbreak in West Africa, Study Says

TUESDAY, Dec. 30, 2014 (HealthDay News) -- The Ebola epidemic in West Africa may have started with virus-infected bats, a new study says.

Ebola epidemics are "zoonotic" in origin, spreading to humans through contact with bats or larger wildlife, according to the researchers in Germany.

But their investigation ruled out larger wildlife as the source of the 2014 outbreak, which began in the Guinean village of Meliandou.

"We monitored the large mammal populations close to the index village Meliandou in southeastern Guinea and found no evidence for a concurrent outbreak," said the study's leader, Fabian Leendertz, from the Robert Koch Institute in Berlin, in an institute news release.

Bats, however, do have contact with humans in Meliandou. And one type of bat in particular -- free-tailed insectivorous bats -- may be a plausible source of transmission, the researchers determined.

So far the Ebola virus has killed about 7,700 people and sickened 20,000, mostly in the West African countries of Sierra Leone, Guinea and Liberia.

The study, published Dec. 30 in EMBO Molecular Medicine, was conducted by a multidisciplinary team of researchers. Over a four-week field mission in Guinea last April, the researchers examined human exposure to bats. They also surveyed local wildlife and collected sample bats in Meliandou and nearby forests.

Interviews with local residents revealed that direct contact with fruit bats through hunting and eating meat is common in the affected regions of Africa. But the researchers determined that fruit bats are not the likely source of the outbreak.

The first case of infection in Meliandou was a 2-year-old boy. Food-related transmission would have affected adults before or at the same time as the boy, the researchers explained.

However, a large colony of free-tailed insectivorous bats lived in a hollow tree near the toddler's home. Villagers reported that children played in and around the tree, which could have led to significant exposure to bats, the study said.